Modafinil (C15H15NO2S) of formula I, 2-(benzhydrylsulfinyl) acetamide, or 2-[(diphenylmethyl) sulfinyl] acetamide, is a synthetic acetamide derivative with wake-promoting activity, the structure of which has been described in U.S. Pat. No. 4,177,290 (“the '290 patent”), and whose racemate has been approved by the United States Food and Drug Administration for use in the treatment of narcolepsy. 
A method of preparation of a racemic mixture is described in the '290 patent. A method of preparation of a levorotary isomer is further described in the U.S. Pat. No. 4,927,855 (both incorporated herein by reference).
Modafinil has been described as a compound having an interesting neuropsychopharmacological potential in mouse (U.S. Pat. No. 4,177,290). Modafinil also induces an important increase in night activity of monkey (Y. Duteil et al., Eur. J. Pharmacol., 1990; 180:49). Modafinil has been successfully tested in humans for treatment of idiopathic hypersomnia and narcolepsy (Bastuji et al., Prog. Neuropsych. Biol. Psych., 1988; 12:695).
Modafinil has also been described as an agent with activity on the central nervous system, and as a useful agent in the treatment of Parkinson's disease (U.S. Pat. No. 5,180,745), in the protection of cerebral tissue from ischemia (U.S. Pat. No. 5,391,576), in the treatment of urinary and fecal incontinence (U.S. Pat. No. 5,401,776), and in the treatment of sleep apneas and disorders of central origin (U.S. Pat. No. 5,612,379).
U.S. Pat. Re. 37,516 describes modafinil preparations of a defined particle size of less than about 200 microns that are more effective and safer than preparations containing a substantial proportion of larger particles.
Beside, these patents that relate to modafinil as racemate, U.S. Pat. No. 4,927,855 discloses the use of the levorotary isomer to treat depression, and disorders present in patients suffering from Alzheimer's disease.
Other therapeutic indications that relate to modafinil racemate are disclosed in more recent patent applications. For instance, international patent application. WO 00/54648 relates to the treatment of vigilance disorders of Steinert's disease, and international patent application WO 99/25329 relates to the treatment of hypersomnia in cancer patients that are administered with morphinic antalgics. Other known therapeutic indications include the treatment of attention deficit hyperactivity disorders (ADHD) linked to hyperactivity and treatment of tiredness and/or fatigue, particularly tiredness and/or fatigue associated to multiple sclerosis (international patent application WO 01/12170), as well as treatment of food behaviour disorders, wherein modafinil is active as an appetite stimulant (international patent application WO 01/13906). International patent application WO 01/13906 also suggests using low doses of modafinil (1 to 75 mg/day) to stimulate cognitive functions, without observing any improvement at higher doses.
The international patent application WO 02/10125 discloses polymorphs of modafinil and processes for preparing them.